Methods for forming polyolefins can include passing a stream having olefin monomers to a polymerization reactor to contact a catalyst and form the polyolefin. However, problems may arise that reduce the catalyst efficiency. For example, high efficiency catalysts may experience a reduced efficiency when exposed to poisons that may be present in polymerization reactors. Therefore, it is desirable to remove a significant portion of the poisons from an input stream prior to the input stream entering the reactor.